/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
using System;
using java = biz.ritter.javapi;

namespace org.apache.commons.codec.binary
{

    /**
     * Provides Base64 encoding and decoding in a streaming fashion (unlimited size). When encoding the default lineLength
     * is 76 characters and the default lineEnding is CRLF, but these can be overridden by using the appropriate
     * constructor.
     * <p>
     * The default behaviour of the Base64InputStream is to DECODE, whereas the default behaviour of the Base64OutputStream
     * is to ENCODE, but this behaviour can be overridden by using a different constructor.
     * </p>
     * <p>
     * This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose
     * Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and Borenstein.
     * </p>
     * <p>
     * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode
     * character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
     * </p>
     * 
     * @author Apache Software Foundation 
     * @version $Id: Base64InputStream.java 799805 2009-08-01 04:33:05Z ggregory $
     * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
     * @since 1.4
     */
    public class Base64InputStream : java.io.FilterInputStream
    {

        private readonly bool doEncode;

        private readonly Base64 base64;

        private readonly byte[] singleByte = new byte[1];

        /**
         * Creates a Base64InputStream such that all data read is Base64-decoded from the original provided InputStream.
         * 
         * @param in
         *            InputStream to wrap.
         */
        public Base64InputStream(java.io.InputStream inJ) :
            this(inJ, false)
        {
        }

        /**
         * Creates a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original
         * provided InputStream.
         * 
         * @param in
         *            InputStream to wrap.
         * @param doEncode
         *            true if we should encode all data read from us, false if we should decode.
         */
        public Base64InputStream(java.io.InputStream inJ, bool doEncode) :
            base(inJ)
        {
            this.doEncode = doEncode;
            this.base64 = new Base64();
        }

        /**
         * Creates a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original
         * provided InputStream.
         * 
         * @param in
         *            InputStream to wrap.
         * @param doEncode
         *            true if we should encode all data read from us, false if we should decode.
         * @param lineLength
         *            If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to
         *            nearest multiple of 4). If lineLength <=0, the encoded data is not divided into lines. If doEncode is
         *            false, lineLength is ignored.
         * @param lineSeparator
         *            If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n).
         *            If lineLength <= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
         */
        public Base64InputStream(java.io.InputStream inJ, bool doEncode, int lineLength, byte[] lineSeparator) :
            base(inJ)
        {
            this.doEncode = doEncode;
            this.base64 = new Base64(lineLength, lineSeparator);
        }

        /**
         * Reads one <code>byte</code> from this input stream.
         * 
         * @return the byte as an integer in the range 0 to 255. Returns -1 if EOF has been reached.
         * @throws IOException
         *             if an I/O error occurs.
         */
        public int read()
        {//throws IOException {
            int r = read(singleByte, 0, 1);
            while (r == 0)
            {
                r = read(singleByte, 0, 1);
            }
            if (r > 0)
            {
                return singleByte[0] < 0 ? 256 + singleByte[0] : singleByte[0];
            }
            return -1;
        }

        /**
         * Attempts to read <code>len</code> bytes into the specified <code>b</code> array starting at <code>offset</code>
         * from this InputStream.
         * 
         * @param b
         *            destination byte array
         * @param offset
         *            where to start writing the bytes
         * @param len
         *            maximum number of bytes to read
         * 
         * @return number of bytes read
         * @throws IOException
         *             if an I/O error occurs.
         * @throws NullPointerException
         *             if the byte array parameter is null
         * @throws IndexOutOfBoundsException
         *             if offset, len or buffer size are invalid
         */
        public int read(byte[] b, int offset, int len)
        {//throws IOException {
            if (b == null)
            {
                throw new java.lang.NullPointerException();
            }
            else if (offset < 0 || len < 0)
            {
                throw new java.lang.IndexOutOfBoundsException();
            }
            else if (offset > b.Length || offset + len > b.Length)
            {
                throw new java.lang.IndexOutOfBoundsException();
            }
            else if (len == 0)
            {
                return 0;
            }
            else
            {
                if (!base64.hasData())
                {
                    byte[] buf = new byte[doEncode ? 4096 : 8192];
                    int c = inJ.read(buf);
                    // A little optimization to avoid System.arraycopy()
                    // when possible.
                    if (c > 0 && b.Length == len)
                    {
                        base64.setInitialBuffer(b, offset, len);
                    }
                    if (doEncode)
                    {
                        base64.encode(buf, 0, c);
                    }
                    else
                    {
                        base64.decode(buf, 0, c);
                    }
                }
                return base64.readResults(b, offset, len);
            }
        }

        /**
         * {@inheritDoc}
         * 
         * @return false
         */
        public bool markSupported()
        {
            return false; // not an easy job to support marks
        }
    }
}